Other than a few exceptions, the show featured just two directors over 9 seasons. Tom Cherones directed all but 5 episodes in seasons 1-5 (1990-1994) for a total of 81 episodes, and Andy Ackerman directed all but 2 episodes in seasons 6-9 (1994-1998), totaling 98 episodes.
INTERESTINGLY, our buddy Jason Alexander directed one episode - The Good Samaritan (1992) - the only time a cast member took over such duties. Did you notice anything unique about that one?
Check out a list of directors and writers by he episode and season here.